Purpose: The contributions of biobehavioral factors in the pathogenesis of hypertension and concentric left ventricular hypertrophy are being investigated. A biracial sample totaling 200 normotensive and borderline hypertensive men and women, aged 25-39 years, and 150 pre- and post- menopausal women, aged 48-55 years, are to be tested. Concentric left ventricular hypertrophy and concentric remodeling are assessed by echocardiographic measures of left ventricular mass and relative wall thickness. Laboratory procedures are used to: (i) assess hemodynamic and neurohumoral responses during exposure to a diverse battery of physical and psychological stressors, and; (ii) evaluate and adrenergic receptor responsiveness, baroreceptor reflex gain and vascular structure. Since blood pressure during a typical workday is an established predictor of left ventricular hypertrophy, it will also be assessed. A new biobehavioral model will be tested that implicates the hemodynamic pattern of behaviorally-evoked pressor responses in the pathogenesis of concentric left ventricular hypertrophy. One prediction of this model is that a predisposition to exhibit increased vascular resistance during stress (characteristic of African American men) will favor the development of concentric hypertrophy. Thus, systemic vascular resistance responses, evaluated in the laboratory, are hypothesized to independently predict left ventricular mass and relative wall thickness, even after controlling for established risk factors, including workday blood pressure. Sympathetic nervous system function will be examined to test hypothesized mechanisms responsible for ethnic, gender and menopause effects on the hemodynamic patterns of blood pressure regulation.